bug#33205: 26.1; unibyte/multibyte missing in rx.el

[Mattias Engdegård]

tis 2018-10-30 klockan 19:27 +0200 skrev Eli Zaretskii:
> I think it's a documentation bug: [:unibyte:] matches only ASCII
> characters.  IOW, it tests "unibyteness" in the internal
> representation (which might be surprising, I know).
> 
> And [:nonascii:] is only defined for multibyte characters.

Thus [:ascii:]/[:nonascii:] cannot be distinguished from
[:unibyte:]/[:multibyte:]. Surely this cannot have been the intention?
Perhaps it's a relic from an earlier implementation. The code certainly
differs (IS_REAL_ASCII vs ISUNIBYTE).

Taking a step back: Do you agree that the missing unibyte/multibyte
should be added to rx, or do you feel that their current relative
uselessness would have them better stay out of it? (I'm neutral on the
subject.)

If there is a useful interpretation of [:unibyte:]/[:multibyte:] today,
perhaps we could make them behave that way.